1. Field of the Invention
The present invention relates to electrostatic precipitators and in particular to a method and apparatus for cleaning the precipitator during gas cleaning operations.
2. Description of the Prior Art
In a typical electrostatic precipitator, a plurality of charged and grounded electrode plates are alternately arranged to electrostatically treat a dirty gas stream flowing between the plates to remove particulates entrained in the gas stream during gas cleaning operations. In such arrangements, it has often been the practice to coat the electrode plates with a suitable film of adhesive to enhance capture and retention of the particulates as the gas stream flows through the precipitator. However, when this is done, it is periodically necessary to stop precipitating operations so the accumulated particulates can be cleaned off the plates before precipitating operations can be continued.
U.S. Pat. No. 3,505,786 shows an electrostatic precipitator which is fairly typical of those currently in use. In that arrangement, a plurality of nozzles are positioned on the upstream side of the electrode plates which are adapted to periodically direct a spray of washing fluid onto the plates when precipitating operations are interrupted to flush away the accumulated particulates on the plates.
While arrangements such as the foregoing have been satisfactory in many applications, it requires that precipitating operations be interrupted while the electrode plates are being cleaned since excessive fluid on the plates tends to promote arcing or electrical shorting between the plates of the precipitator if they are flushed when they are energized. Arcing of this nature has been found to significantly reduce the efficiency of the power supply used to energize the precipitator, and in some applications such arcing renders the precipitator totally inoperative until the fluid drains from the plates. Thus, although temporarily interrupting the precipitating process is acceptable in some applications, in the typical industrial application where the unit is used to remove various vapors and the like from machine operator's work stations, it has generally been necessary to also shutdown the machinery generating the vapors until the flushing operation is completed. This, of course, can result in costly machine downtime and operator expense when unforeseen scheduling problems develop during routine manufacturing operations.